Is heroin addiction related to a dysfunctional processing of reward and hedonism in the brain? Insights from neuroimaging studies

The functioning of reward in drug addicts is a major issue both in terms of
pathophysiology and in a rehabilitative view. We used a PET imaging device
to assess the hedonic functioning of methadone maintained heroin addicts,
compared to control subjects, by two modalities: 1) the elicitation of interest by
anticipated monetary reward; 2) the neuroimaging correlates of visually elicited
pleasure. In heroin addicts fewer brain regions showed activated during tasks
implying known monetary reward in comparison to tasks without any reward.
On the other hand, the processing of subjectively pleasant videoclips resorted to
different brain pathways in heroin addicts. Heroin addicts seem to show a lower
level of anticipatory sensitivity to monetary reward, whereas the topography of
pleasure-feeling seems to be different from normal subjects’. Such results show
a different reward-seeking and reward-feeling status of methadone maintained
heroin addicts, although it is to be clarified whether such a status was also forerunning
heroin use, or developed as a correlate of addiction